
<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			div{
				width: 100px;
				height: 100px;
			}
			.box1{
				background-color: blue;
			}
			.box2{
				background-color: green;
				margin-top: 2px;
				margin-bottom: 2px;
				/* margin: 10px; */ /* 代表四个方向值都是一致的 */
				border: 5px solid red;
				padding: 10px;
			}
		</style>
	</head>
	<body>
		<div class="box1"></div>
		<div class="box2"></div>
		<div class="box1"></div>
	</body>
</html>